<Swing Dev> RFR JDK-8240995:[macos] Unified toolbar is broken in JDK 11

[Prasanta Sadhukhan]

Hi All,

Please review a fix for a mac issue where it is seen that Unified 
toolbar or textured background enabled by "apple.awt.brushMetalLook" is 
not working.

Issue is because of the fact that with migration to new SDK by 
JDK-8205424, the flags used to specify textured background for NSWindow 
is deprecated and we did not update the code with new flag.

Fix is to use new flags as specified by apple doc.

Bug: https://bugs.openjdk.java.net/browse/JDK-8240995

webrev: http://cr.openjdk.java.net/~psadhukhan/8240995/webrev.0/

Regards
Prasanta